docs: def _normalize_slice(self, key, clamp=False):
          """Return a slice equivalent to the input *key*, standardized."""
          if key.start is None:
              start = 0
          else:
              start = (len(self) + key.start) if key.start < 0 else key.start
          if key.stop is None or key.stop == maxsize:
              stop = len(self) if clamp else None
          else:
              stop = (len(self) + key.stop) if key.stop < 0 else key.stop
          return slice(start, stop, key.step or 1)